1. Field of the Invention
The invention relates to a fingerprint identification technique, and specially regards a fingerprint identification system, a driving circuit, and a fingerprint identification method.
2. Description of Related Art
In the fields of fingerprint identification, fingerprint identification techniques are categorized into optical, thermo-sensitive, ultrasonic, and capacitive techniques. These fingerprint identification techniques have different application and combinations in current different electronic devices. Specially, the capacitive fingerprint identification technique has widespread applications now, and the fingerprint identification method focuses on the identification of the ridge-valley patterns of fingerprints to obtain fingerprint information. Due to the different ridge-valley patterns on fingerprints, when fingerprints contact the sensing panel, the capacitance of different sensing regions on the sensing panel may change in respect to different patterns. The sensing capacitance is smaller in the valley portion of the fingerprints and the ridge portion of the fingerprints has larger sensing capacitance. However, the ridge-valley difference of the pattern is minute, corresponding to a difference of sensing capacitance of only 0.1 farad to 1 farad on the sensing panel. Therefore, when conducting the fingerprint identification in the presence of noise interference, the fingerprint identification system may be influenced easily by the noise as the system receives the sensing signal regarding the changes in capacitance to analyse the changes in capacitance. The accuracy of the fingerprint identification may be influenced by the misjudgement of the signal. Thus, it is a very important issue to overcome noise interference to increase the accuracy of fingerprint identification.